"""
This file contains the code to create a PR or update an existing one based on the state of the current branch.
"""

import logging
import os
import subprocess  # nosec
from contextlib import contextmanager
from os import chdir, environ, getcwd
from pathlib import Path

import requests
from check_updated_packages import get_changed_dependencies

REPO_DIR = Path(__file__).parent.parent / 'napari_repo'
# GitHub API base URL
BASE_URL = 'https://api.github.com'
DEFAULT_BRANCH_NAME_PREFIX = 'auto-update-dependencies'
DEFAULT_BRANCH_NAME = f'{DEFAULT_BRANCH_NAME_PREFIX}-main'


@contextmanager
def cd(path: Path):
    """
    Change directory to the given path and return to the previous one afterwards.
    """
    current_dir = getcwd()
    try:
        chdir(path)
        yield
    finally:
        chdir(current_dir)


def _setup_git_author():
    subprocess.run(
        ['git', 'config', '--global', 'user.name', 'napari-bot'], check=True
    )  # nosec
    subprocess.run(
        [
            'git',
            'config',
            '--global',
            'user.email',
            'napari-bot@users.noreply.github.com',
        ],
        check=True,
    )  # nosec


def create_commit(message: str, branch_name: str = ''):
    """
    Create a commit calling git.
    """
    with cd(REPO_DIR):
        if branch_name:
            subprocess.run(['git', 'checkout', '-B', branch_name], check=True)
        subprocess.run(['git', 'add', '-u'], check=True)  # nosec
        subprocess.run(['git', 'commit', '-m', message], check=True)  # nosec


def push(branch_name: str, update: bool = False):
    """
    Push the current branch to the remote.
    """
    try:
        with cd(REPO_DIR):
            logging.info('go to dir %s', REPO_DIR)
            if update:
                logging.info('Pushing to %s', branch_name)
                subprocess.run(
                    [
                        'git',
                        'push',
                        '--force',
                        '--set-upstream',
                        'napari-bot',
                        branch_name,
                    ],
                    check=True,
                    capture_output=True,
                )
            else:
                logging.info('Force pushing to %s', branch_name)
                subprocess.run(
                    [
                        'git',
                        'push',
                        '--force',
                        '--set-upstream',
                        'napari-bot',
                        branch_name,
                    ],
                    check=True,
                    capture_output=True,
                )  # nosec
    except subprocess.CalledProcessError as e:
        stdout = e.stdout.decode() if e.stdout else ''
        stderr = e.stderr.decode() if e.stderr else ''
        logging.exception(
            'Error pushing to branch %s:\n\nstdout: %s\n\nstderr: %s\n\nWith error %d',
            branch_name,
            stdout,
            stderr,
            e.returncode,
        )
        raise


def commit_message(branch_name) -> str:
    with cd(REPO_DIR):
        changed_direct = get_changed_dependencies(
            all_packages=False,
            base_branch=branch_name,
            python_version='3.11',
            src_dir=REPO_DIR,
        )
    if not changed_direct:
        return 'Update indirect dependencies'
    return 'Update ' + ', '.join(f'`{x}`' for x in changed_direct)


def long_description(branch_name: str) -> str:
    with cd(REPO_DIR):
        all_changed = get_changed_dependencies(
            all_packages=True,
            base_branch=branch_name,
            python_version='3.11',
            src_dir=REPO_DIR,
        )
    return 'Updated packages: ' + ', '.join(f'`{x}`' for x in all_changed)


def create_pr_with_push(branch_name: str, access_token: str, repo=''):
    """
    Create a PR.
    """
    new_branch_name = f'{DEFAULT_BRANCH_NAME_PREFIX}-{branch_name}'

    if not repo:
        repo = os.environ.get('GITHUB_REPOSITORY', 'napari/napari')
    with cd(REPO_DIR):
        subprocess.run(['git', 'checkout', '-B', new_branch_name], check=True)
    create_commit(commit_message(branch_name))
    push(new_branch_name)

    logging.info('Create PR for branch %s', new_branch_name)
    if pr_number := list_pr_for_branch(
        new_branch_name, access_token, repo=repo
    ):
        update_own_pr(pr_number, access_token, branch_name, repo)
    else:
        create_pr(
            base_branch=branch_name,
            new_branch=new_branch_name,
            access_token=access_token,
            repo=repo,
            source_user='napari-bot',
        )


def update_own_pr(pr_number: int, access_token: str, base_branch: str, repo):
    headers = {'Authorization': f'token {access_token}'}
    payload = {
        'title': commit_message(base_branch),
        'body': long_description(base_branch),
    }
    url = f'{BASE_URL}/repos/{repo}/pulls/{pr_number}'
    logging.info('Update PR with payload: %s in %s', str(payload), url)
    response = requests.post(url, headers=headers, json=payload)
    response.raise_for_status()

    url_labels = f'{BASE_URL}/repos/{repo}/issues/{pr_number}/labels'
    response = requests.get(url_labels, headers=headers)
    response.raise_for_status()

    remove_label_url = (
        f'{BASE_URL}/repos/{repo}/issues/{pr_number}/labels/ready%20to%20merge'
    )

    # following lines is to check if "ready to merge" label is added to PR,
    # if it is present, then remove it to point that PR was changed
    for label in response.json():
        if label['name'] == 'ready to merge':
            response = requests.delete(remove_label_url, headers=headers)
            response.raise_for_status()
            break


def list_pr_for_branch(
    branch_name: str,
    access_token: str,
    repo: str = 'napari/napari',
    user: str = 'napari-bot',
):
    """
    check if PR for branch exists
    """
    url = f'{BASE_URL}/repos/{repo}/pulls?state=open&head={user}:{branch_name}'
    response = requests.get(url)
    response.raise_for_status()
    if response.json():
        return response.json()[0]['number']
    return None


def create_pr(
    base_branch: str, new_branch: str, access_token: str, repo, source_user=''
):
    # Prepare the headers with the access token
    headers = {'Authorization': f'token {access_token}'}

    # publish the comment
    payload = {
        'title': commit_message(base_branch),
        'body': long_description(base_branch),
        'head': new_branch,
        'base': base_branch,
        'maintainer_can_modify': True,
    }
    if source_user:
        payload['head'] = f'{source_user}:{new_branch}'
    pull_request_url = f'{BASE_URL}/repos/{repo}/pulls'
    logging.info(
        'Create PR with payload: %s in %s', str(payload), pull_request_url
    )
    response = requests.post(pull_request_url, headers=headers, json=payload)
    response.raise_for_status()
    logging.info('PR created: %s', response.json()['html_url'])
    add_label(repo, response.json()['number'], 'maintenance', access_token)


def add_label(repo, pr_num, label, access_token):
    pull_request_url = f'{BASE_URL}/repos/{repo}/issues/{pr_num}/labels'
    headers = {'Authorization': f'token {access_token}'}
    payload = {'labels': [label]}

    logging.info('Add labels: %s in %s', str(payload), pull_request_url)
    response = requests.post(pull_request_url, headers=headers, json=payload)
    response.raise_for_status()
    logging.info('Labels added: %s', response.json())


def add_comment_to_pr(
    pull_request_number: int,
    message: str,
    repo='napari/napari',
):
    """
    Add a comment to an existing PR.
    """
    # Prepare the headers with the access token
    headers = {'Authorization': f'token {os.environ.get("GITHUB_TOKEN")}'}

    # publish the comment
    payload = {'body': message}
    comment_url = (
        f'{BASE_URL}/repos/{repo}/issues/{pull_request_number}/comments'
    )
    response = requests.post(comment_url, headers=headers, json=payload)
    response.raise_for_status()


def update_pr(branch_name: str):
    """
    Update an existing PR.
    """
    pr_number = get_pr_number()

    target_repo = os.environ.get('FULL_NAME')

    new_branch_name = f'auto-update-dependencies/{target_repo}/{branch_name}'

    if (
        target_repo == os.environ.get('GITHUB_REPOSITORY', 'napari/napari')
        and branch_name == DEFAULT_BRANCH_NAME
    ):
        new_branch_name = DEFAULT_BRANCH_NAME

    create_commit(commit_message(branch_name), branch_name=new_branch_name)
    comment_content = long_description(f'origin/{branch_name}')

    try:
        push(new_branch_name, update=branch_name != DEFAULT_BRANCH_NAME)
    except subprocess.CalledProcessError as e:
        if 'create or update workflow' in e.stderr.decode():
            logging.info('Workflow file changed. Skip PR create.')
            comment_content += (
                '\n\n This PR contains changes to the workflow file. '
            )
            comment_content += 'Please download the artifact and update the constraints files manually. '
            comment_content += f'Artifact: https://github.com/{os.environ.get("GITHUB_REPOSITORY", "napari/napari")}/actions/runs/{os.environ.get("GITHUB_RUN_ID")}'
        else:
            raise
    else:
        if new_branch_name != DEFAULT_BRANCH_NAME:
            comment_content += update_external_pr_comment(
                target_repo, branch_name, new_branch_name
            )

    add_comment_to_pr(
        pr_number,
        comment_content,
        repo=os.environ.get('GITHUB_REPOSITORY', 'napari/napari'),
    )
    logging.info('PR updated: %s', pr_number)


def update_external_pr_comment(
    target_repo: str, branch_name: str, new_branch_name: str
) -> str:
    comment = '\n\nThis workflow cannot automatically update your PR or create PR to your repository. '
    comment += 'But you could open such PR by clicking the link: '
    comment += f'https://github.com/{target_repo}/compare/{branch_name}...napari-bot:{new_branch_name}.'
    comment += '\n\n'
    comment += 'You could also get the updated files from the '
    comment += f'https://github.com/napari-bot/napari/tree/{new_branch_name}/resources/constraints. '
    comment += 'Or ask the maintainers to provide you the contents of the constraints artifact '
    comment += f'from the run https://github.com/{os.environ.get("GITHUB_REPOSITORY", "napari/napari")}/actions/runs/{os.environ.get("GITHUB_RUN_ID")}'
    return comment


def get_pr_number() -> int:
    """
    Get the PR number from the environment based on the PR_NUMBER variable.

    Returns
    -------
    pr number: int
    """
    pr_number = environ.get('PR_NUMBER')
    logging.info('PR_NUMBER: %s', pr_number)
    return int(pr_number)


def main():
    event_name = environ.get('GITHUB_EVENT_NAME')
    branch_name = environ.get('BRANCH')

    access_token = environ.get('GHA_TOKEN_MAIN_REPO')

    _setup_git_author()

    logging.basicConfig(level=logging.INFO)
    logging.info('Branch name: %s', branch_name)
    logging.info('Event name: %s', event_name)

    if event_name in {'schedule', 'workflow_dispatch'}:
        logging.info('Creating PR')
        create_pr_with_push(branch_name, access_token)
    elif event_name == 'issue_comment':
        logging.info('Updating PR')
        update_pr(branch_name)
    elif event_name == 'pull_request':
        logging.info(
            'Pull request run. We cannot add comment or create PR. Please download the artifact.'
        )
    else:
        raise ValueError(f'Unknown event name: {event_name}')


if __name__ == '__main__':
    main()
